House Speaker John Boehner's promise on Wednesday to balance the federal budget "over the next 10 years" was aimed at convincing Tea Party conservatives in Congress to hold their fire over a bill to temporarily raise the U.S. debt ceiling.

But carrying it out would require spending cuts or revenue increases far greater than anything seriously considered by Congress in recent years, including the budget passed by the Republican-controlled House last March, which envisioned shrinking deficits to $3.13 trillion over 10 years in part by a total revamp of Medicare and Medicaid, the government health insurance programs for seniors and the poor.

That budget resolution, drawn up by House Budget Committee Chairman Paul Ryan, projected a balanced budget not in 10 years, but by 2040.

"It seems politically unrealistic to think you could get to a balanced budget" in a decade, said Robert Bixby, executive director of the Concord Coalition, a non-partisan organization devoted to deficit reduction.

That's particularly true, Bixby said, in view of the Republican vow to avoid further tax increases for deficit reduction.

"I don't see it," said Bixby, adding that "it'll be a very useful exercise to see how" Boehner might do it.

Boehner, speaking after the House passed a bill to allow the federal government to borrow more money until May 19, provided no details on how Republicans would keep the promise, leaving Ryan - the Republican 2012 vice presidential nominee - and his budget committee to work it out in the weeks ahead.

The federal budget was last balanced in 2001, thanks in part to a tax increase, low unemployment and a booming economy. Although taxes on the wealthiest Americans have gone up as the result of a fiscal deal reached in early January, unemployment remains stubbornly high and the U.S. economic recovery is tepid.

The government has been running annual deficits of about $1 trillion for the past four years, according to the Congressional Budget Office, so something dramatic would have to occur to wipe out those imbalances in 10 years.

The government spends about $1.2 trillion on military and domestic programs known as "discretionary" because they can be cut, and about $2.1 trillion on so-called mandatory programs, including Medicare, Medicaid, entitlements which grow automatically according to demand and provider cost.

The 2010 Simpson-Bowles Commission on Fiscal Responsibility projected annual deficits of $279 billion through the year 2020 and that after reforming the tax code and cutting the costs of Social Security, Medicare and Medicaid, among other things.

The last major politician to promise to deliver a balanced budget in 10 years was Republican 2012 presidential nominee Mitt Romney.